Please, know that these practices and materials are very real, and there is risk in this work, just as in chemistry. But with the necessary precautions, for those who do venture forth, there is real wisdom to be found. When this practice is joined with the intent to heal or something positive, things happen.
Start slowly and mindfully, put consistent effort behind the work and go through a few of the processes at a time. The basics are here, but reach into the primary sources from which these practices come and read them against your own practice and results. Dig into it, ask questions of the matter at hand, investigate it and not timidly. Soon you will clearly see that it is not a metaphor for something else, but rather that alchemy is fundamentally about transmutation in the physical world—of change from poison to medicine, from sickness to health, poverty to wealth, and ignorance to wisdom.